Cathode ray tube control matrix employing magnetic shields



Aug. 24, 1965 Filed Jan. 28, 1963 J. J. STONE ETAL CATHODE RAY TUBECONTROL MATRIX EMPLOYING MAGNETIC SHIELDS 3 Sheets-Sheet 1 umacoum H IRNG grip COUNT7 VE RT\CAL HORIZONTAL J CO U NT ER $WEEP SWEEP GENERATORGENERATOR \6/ l I 0 u no I a r a i I CHARACTER Z GENERATOR MATRM 2o B1ASSOURCE 22 4'1F' 1I 1 H 4 ,26 52a 50 52:: 52 52A 3 (O O O O I I 50 50A I9 9 I M95 AsA D b 1% l 46 l 46A 3 3 (0 o o o '44A gm M21, I I 54 H l l IV 17- |,\\4 I ,ue I,\\8 CHARACTER CHARACTER CHARACTER 5$6NAL swam.sew/m. )28 GEN. GEN. GEN. CATHODE 1 20 22 f \24 R w \s LAY 5 5 5 2 GATE5 G A116 6 ATES APPARATUS CHARACTER J j SELECTlON SOURCE ,uz ,uo c; N GJOSEPH J g 7 LOCK COUNT-ER ROMA/V A. ADAMS BY 075M 1- 7 k A 7TORNEY Aug.24, 1965 Filed Jan. 28, 1965 MATR\X CARD DR\VER AMPLIFlERS CLOCK PULSE.GEN.

J. J. STONE ETAL 3,202,980

CATHODE RAY TUBE CONTROL MATRIX EMPLOYING MAGNETIC SHIELDS 3Sheets-Sheet 2 SENSE AMPUFIERS a2 DELAY LINE 94 OUTPUT PULSE R\NGCOUNTER 28-2 CLOCK 96 98 100 PULSE ll H; [L FL DRWER 64A AMP. j 127 4A72A 5 Hf 94A 94B .940 2312;; /O5 H./ STONE POM/Ml A.ADAM$ HOR\ZONTAL INEN "SWEEP I 2 3 I 4 5 V was PULBE": BY g 2 z ff' n4 A 77'ORNE Y 24, 1 J.J. STONE ETAL 3,202,980

CATHODE RAY TUBE CONTROL MATRIX EMPLOYING MAGNETIC SHIELDS Filed Jan.28, 1963 3 Sheets-Sheet 3- A SENSE \NHIEHT AMPLlFlER5 GATES DELAV 52 2UNE METAL 3o 52 SH\ELD DRIVER AMPLIFIERS Rme COUNTER 1 g. 5

CLOCK 96 PULSES H H H H H SENSE AMP? 76A 2 H 2 J1 vaA H 3 80A aoA 6 4 1+n n 82A 82A 82A 5 H J H fl H 94A 4 OUTPUT nnfl i PULSES JOSEPH J. STONEg$gg 2 3 I 4 5 @QMA/v A.AOAMs PERiODs INVENTORS v BJMW A 7TORNEY UnitedStates Patent CATHODE RAY TUBE CONTROL MATRIX EM- PLOYING MAGNETICSHIELDS Joseph .1. Stone, Glenview, and Roman A. Adams, Skokie,

111., assignors to A. B. Dick Company, Chicago, 111., a corporation ofIllinois Filed Jan. 28, 1963, Ser. No. 254,137

8 Claims. (Cl. 340-324) This invention relates to character generatorsand more particularly to improvements therein.

Various ditferent constructions have been devised in order to generatesignals, which, when displayed on cathode ray tube apparatus, representa character. Such structures range from a resistor voltage divider withprovision for gating voltage amplitudes from the various tapping pointson the divider and thereafter displaying these, to employing a monoscopetube having characters or symbols drawn on its target, selectivelyscanning the desired character or symbol, and thereafter applying thesignals derived from the monoscope tube as a result of this scanning, toa subsequent cathode ray tube system for proper display.

While these systems are eifective and adequate for the purpose ofproviding the proper character signals, they all have a common failing.Once they are constructed they are fixed with respect to the charactersor symbols to be represented. They do not provide for changes or for asimple mechanism for making changes in the generated character signals.Also, the equipment involved is rather expensive.

An object of this invention is the provision'of a character signalgenerating system which enables a change for generating differentcharacter signals to be made in a very simple manner.

Yet another object of the present invention is the provision of a systemfor generating character signals, the cost of which is relativelyinexpensive.

Still another object of the present invention is the provision of anovel and unique system for generating character signals.

These and other objects of the present invention are achieved byproviding two separate sets of conductors, the conductors of each setextending parallel to one another, the conductors of one set beingpositioned orthogonally with relation to the position of the conductorsof the second set. Where the orthogonally related conductors intersect,they are formed into a half loop, so that if a currentpulse is appliedto one of the conductors of one of the sets, there is an air coupling toall of the conductors of the other set at the intersection whereby avoltage may be detected at the output of each one of the conductors inthe second set.

In order to use this arrangement for generating character signals, amagnetic shielding material is inserted between the orthogonallypositioned sets of conductors, which shielding material substantiallyprevents air coupling between the orthogonally related conductors atpredetermined ones of the intersections. If a means for sequentiallyexciting the conductors of the first set is provided, and the outputs ofthe conductors of the second set are amplified and applied to tappingpoints along a multi-tapped delay line, for any given sequentialapplication of current to the linesof the first set, a sequence ofpulses is emitted for each line from the output of the multi-tappeddelay line, which when displayed line by line on a cathode ray tubeface, represents the character desired.

The novel features that are considered characteristic of this inventionare set forth with particularity in the appended claims. The inventionitself, both as to its orice ganization and method of operation, as wellas additional objects and advantages thereof, will best be understoodfrom the following description when read in connection with theaccompanying drawings, in which:

FIGURE 1 is a block diagram illustratingan arrangernent for displaying acharacter generated by an embodiment of this invention.

FIGURE 2 is a drawing of printed circuit boards in accordance withthisinvention.

FIGURE 3 is a schematic diagram illustrating an embodiment of thisinvention.

FIGURE 4 is a waveshape drawing illustrating the waveshape generated bythe arrangement shown in FIG. 3.

FIGURE 4A shows the appearance of a dot pattern when no shield materialis inserted between printed circuit boards.

FIGURE 5 is a circuit diagram of another embodiment of the invention.

FIGURE v6 is a waveshape diagram illustrating the pulses generated bythe arrangements shown in FIG- URE 5.

FIGURE 7 is a block diagram of an arrangement for generating anddisplaying a multiplicity of characters on a cathode ray deviceemploying embodiments of this invention. i

Reference is now made to FIGURE 1 which shows a block diagram of cathoderay display apparatus using a character'signalgenerator of the typecomprising this .invention. The diagram is shown to indicate how acharacter signal generator which is an embodiment of this invention maybe incorporated into cathode ray display apparatus. From this, thoseskilled in the art will :have no diificulty in both the comprehensionand construction of the arrangement.

A ring counter 10 has a count capacity which may be determined by thenumber of horizontal lines which are employed to represent a characteron the cathode ray device. The ring counter output is applied toacharacter generator matrix 12, which supplies in response thereto,pulses which are spaced in a manner to represent a charaacter on theface of the cathoderay tube 14, provided that the vertical andhorizontal positioning of the cathode ray beam is proper. To achievethis proper positioning the output of the ring counter is also appliedto a vertical sweep generator 16, and a horizontal sweep generator 18.The horizontal sweep generator 18, applies line deflection voltages tothe cathode ray tube 14, in response to the ring counter output. Eachcount output of the ring counter causes the horizontal sweep generatorto deflect the cathode ray beam across one line. The vertical sweepgenerator 16 applies vertical deflection voltages to the cathode raytube 14. The vertical sweep generator is synchronized to provide avertical deflection voltage equal to the total vertical deflection of acharacter in response to a total count of the ring counter.

In operation a bias source 20, applies a potential to an electrode ofthe cathode ray device 14, for the purpose of biasing oif the cathoderay beam. The ring counter 10 commences counting. Assume that the totalcount capacity of the ring counter is five, therefore, upon the occurrence of the first output of the ring counter, the horizontal sweepgenerator commences deflecting the cathode ray beam horizontally. Outputsignals from the character generator matrix have a suflicient amplitudeto overcome the bias of the source 20. Thus, if it were the letter Ethat were to be displayed on the face of the cathode ray tube 14, thecharacter generator matrix would emit four pulse signals which would bedisplayed along the 0 horizontal line as four bright spots.

Upon the occurrence of a second count output from the ring counter, thevertical sweep generator provides the ver- 7 .tical displacement of thecathode ray beam While the horizontal sweep generator commences sweepinganother line. This time the output of the character generator matrix, inresponse to this second signal, is a single pulse signal resulting in asingle bright spot.

The operation of the system for generating the remainder of the letter Eshould be apparent from the previous description. While the letter B isshown as covering the entire cathode ray.tube' face, those skilled inthe art will readily appreciate the fact that the size of the characterbeing displayed may be easily controlled by the amplitude of the sweepsignals being applied to the cathode ray tube. Also, the letter may bepositioned any place on the face of the tube which is desired, by thesimple 'expedience of adding D.C. voltages to the vertical andhoriozntal sweep voltages. Reference is now made to FIGURE 2, whichshows number of conductors on the vertically oriented circuit board 22,is determined by the number of lines 'of dots or bright spots to'bedisplayed on the cathode ray tube face.

' Thus, in the letter E shown in FIGURE 1, there are five linesofispots, there are five printed circuit conductors respectively 24, 26,28, 30, and 3 2, on the board 22 and five printed circuit conductorsrespectively 44,46, 48, 50,

and 52, on the board 42. Each one of the printed circuit conductorseffectively constitutes five coils connected in series and a returnline. Thus, printed circuit conductor 24, has the five coils 24A, 24B,24C, 24D, and 24E, connected in series and a return line 24'. Similarlyprinted circuit conductor 44 comprises five coils 44A through 44Econnected in series and a return line 44', Each of the printed circuitconductors 24, through 32 and their return lines end in terminals, asfor example 34. .Each of all g the printed circuit conductors 44 through52 and their return lines end in terminals, as for example 54.

All of the printed circuit conductors are insulated, so that upon theplacing of the printed circuit board 42 over j printed circuit board 34,the conductors do not connect with one another. However, such overlay ofone printed circuit board upon the other does form a' matrixin which,

for example, the windings 24Athrough 24B are positioned directlyopposite windings 44Athrough 52A. Accordingly, should a current pulse beapplied to the'conductor 24, each one of the windings 24Athrough'24E'would operate in the manner of the primary winding of atransformer and each one of the windings 44A through 52A would operatein the manner of the secondary windings of a transformer, j whereby avoltage would be induced from eachone of the respective primary windings24A through 24E into each one of the secondary windings respectively SZAthrough To summarize the foregoing,'by placing the printed boards, thenonly those of the windings on the respective boards between which thereis no; shield materiahcan operate as a transformer.

' when displayed, represent a character.

'be designated by a two part reference numeral.

' secondary winding of the transformer lies.

Attention is now called to FIGURE 3, which is a circuit diagramrepresentation of an embodiment of the invention employing thecomponents 22, 42, and 26, as well as others for the purpose ofgenerating signals, which Reference numer als applied to the structuresin FIGURE 3 correspond to those of the structures in FIGURE 2. Since thetwo printed circuit boards are superimposed, as previously stated,transformers are effectively provided at the intersections of theprinted circuit'boards which are represented in FIGURE 3 by circles atthe intersections of the grid of conductors. The circle actuallyrepresents' the appearance of the coils when the boards aresuperimposed. Each one of the transformers which are formed by thesuperimposed printed circuit boards, will The first part indicates thevertical conductor which forms the primary winding portion of thetransformer and the last part is the unit place number of the decimalnumber designating the horizontal conductor in which the Thus, at theintersection of conductors 24 and 44, the transformer 24-4gis formed. Atthe intersection of conductors 28 'and 4 6, the transformer 28-6 isformed. 25

The shield 26, which is placed between the two superimposed printedcircuit boards, prevents magnetic coupling from being establishedbetween primary and secondary windings of the transformers 24-2, 26-2,28-2 and 30-2, and 32-2. Also transformers 26-6, 26-8, 26-0, 28-0, 30-0,30-8, and 30-6. The remaining transformers, which are formed at theintersections of the printed circuit conductors, have their primary andA clock pulse generator 60, applies pulses to drive a 'ring counter 10.Each one of the five outputs of the ring counteris applied to adifferent amplifier circuit respectively 64,66, 68, 70,- 72. Each one ofthese amplifier circuits applies a pulse of current to the respectiveconductors 24, 26, 28, 30, and 32, the other ends of which are grounded.Each one of the conductors 44, 46, 48, and 52 are respectively connectedto pulse amplifiers respectively 74, 76, 78, 80, and '82. The ,0utput ofeach one of these pulse amplifiers is connected to a different tap on amulti-tap delay line 90. The delay line may also be made from aplurality of separate short sections of delay line which are connectedin series with the amplifiers 74 through 82, connected to each one ofthe junctions thereof. The output of the delay line 90 is applied to'aload resistor 92. Output developed across the load resistor 92, is takenfrom an output terminal 94. The signals existingat the output terminal94, may be applied to an electrode of a cathode ray tube such as 14, forthe purpose of overcoming the bias from a bias source, such as 20,whereby a bright spot will be displayed on the face of the cathode raytube.

In operation, when it is desired to display the letter E, the clockpulse generator is enabled, whereby ringcounter 10 is successivelydriven through each one i of its count states; This causes a successionof pulses to y be applied by the amplifiers 64 through 72 to therespective lines 24 through 32. In FIGURE 4, the clock pulses arerepresented by the waveforms 96. The output of the first amplifier 64,,designated by 64A, in FIGURE 4, is applied to the conductor 24. Inresponse thereto, pulsesare induced'in the secondary windings of trans-Jformers 24-4, 24-6, 24-8, and 24-0.. These are applied by therespective amplifiers 74 through to the delay line 90. The delay lineserves the function or presenting these pulses at the output terminals'94, as a pulse interval of the first count, the four pulses in the wavetrain 04A will be represented as four bright spots in line on the faceof the cathode ray tube. 7

Upon the occurrence of the second clock pulse 98, the second amplifier65, applies a pulse of current to the line 26, whereby only a singleoutput will occur on the line 44, since the remaining transformers havetheir primaries shielded from the secondaries by the shield 26. Thisoutput is amplified by amplifier 74, and applied to the output terminal94. Since the pulse occurs without delay, and since the vertical sweepgenerator has initiated a vertical sweep in response to the counteroutput, this pulse is displayed at the beginning of the horizontaldeflection for the second count.

Upon the occurrence of the third clock pulse 100, the third count of thecounter drives the amplifier 68, which in turn applies a current pulseto the primaries of the transformers connected to the line 23. Only thesecondary windings of transformers 284, 28-6, and 28-3 have voltagesinduced therein. In response thereto, the waveshape 94C appears at theoutput terminal 94. This is displayed as the center bar of three dots ofthe letter E.

From the foregoing description it should be apparent how the remainderof the letter E signals are generated as the counter progresses throughits count cycle. It should also be apparent that all that is necessaryto generate pulse wave trains for representing different characters orsymbols, is to substitute, for the pi-shaped shield 26, another shieldwhich blocks coupling between the transformers not required to providethe requisite waveshape, leaving the other transformers with unimpededmagnetic coupling between primary and secondary windings. The format formaking the shield pattern is a very simple one. If there is noshield'present then the character generator will generate a dot patternwhich is rectangular and which effectively provides a dot for eachtransformer present. The desired letter or symbol may be superimposedupon the dot pattern. All of the dots which fall outside of the patternsuperimposed on the symbol indicate which transformers should have ashield inserted between their primary and secondary windings. Sincethere is one to one correspondence between the dots in the dot patternand the transformers formed by the printed circuit boards, this shouldnot prove at all difiicult.

To further exemplify this, attention is called to FIG- URE 4A, whereinthere may be seen a dot pattern which is generated were there no shieldpresent in the circuit arrangement in FIGURE 3. A pattern 102, of thecharacter desired to be displayed, is placed over this dot pattern. Theuncovered dots indicate the transformer which should have theirprimaries shielded from their secondaries. Some of the dots which areuncovered are given the same reference numerals as the transformers fromwhich they are generated, in order to show the one to onecorrespondence. The derivation of the pi-shaped shield 26, forgenerating the letter E should be apparent from this. I

FIGURE 5 is a circuit arrangement of an embodiment of the inventionwhich is substantially identical with that shown in FIGURE 3. However,by changing the output circuitry slightly, it is possible to cut theshield for insertion between the two circuit boards directly in thepattern of the character desired to be displayed. In FIGURE 5 similarlyfunctioning structure is given the same reference numerals-as wereapplied in FIGURE 3. Note here however, that-the shield 104,'has thesame configuration as the letter E which is the character desired fordisplay.

The clock pulse generator 60 not only drives the ring counter 10 in themanner previously described, but also applies its output to a pulseamplifier 106, The output of the pulse amplifier is applied to fiveinhibit gates, respectively 103 through 116. These inhibit gates arewell known two input gate circuits which in the presence of aninhibiting input to one input can prevent the signal applied to theother input of the inhibiting gate from being transferred to the inhibitgate output. The inhibit input to each one ofthe inhibit gates 108through 116, are the respective outputs of the amplifiers 7 4 through02. The pulse amplifier 106 output is the second or inhibit input toeach gate. The outputs of the inhibit gates are connected, in the mannerdescribed in connection with FIGURE 3, t0 the respective taps along themulti-tap delay line 90. The output of the delay line is applied to aload resistor 02 from, across which output is taken by means of theoutput terminal 94.

Upon the occurrence of the first pulse output from the clock pulsegenerator 60, the ring counter 10 applies its first count output to theamplifier 64. This causes a voltage to be induced in the secondary ofthe transformer 24-2. This voltage is amplified by the pulse amplifier82, and is applied to the inhibit gate 116. The clock pulse generator60, also applies an output to the amplifier 106, the output of which isapplied to all of the inhibit gates 108 through 116. Accordingly, eachone of the inhibit gates 108 through 114 will provide an output to thedelay line 90, while the effect of the output of amplifier 82 is .toprevent the inhibit gate 116 from providing an output to thedelay line.

As shown in FIGURE 6, the only amplifier which produces an output inresponse to the first clock pulse 96, is amplifier 82, as represented bythe waveshape 82A. The operation of the inhibit gates is such that thewaveshape 94A occurs at the output terminal 94. This is identical withthe waveshape 94 as is shown in FIGURE 4. Accordingly, upon theoccurrence of the first count of the counter fourdots are displayedalong the first lines on the face of the cathode ray tube.

In response to the occurrence of the second clock pulse from thegenerator 60, the counter is advanced to its second count. As shown inFIGURE 6, inhibit pulses respectively 76A through SZA are generated atthe outputs of the respective amplifiers 76 through 82, whereby the onlypulse that is applied to the delay line is received from the output ofthe inhibit gate 108, since no voltagepulse is applied to the amplifier74, and therefore there isno inhibit pulse applied to the gate 108. Thepulse 94B is displayed at the beginning of the second horizontal line onthe face of the cathode ray tube.

In response to the third clock, pulse, inhibit signals 80A;, and 82A areapplied to the inhibit gates from the outputs of the amplifiers 82 and80. Therefore, a pulse train consisting of three pulses as representedby waveshape 94C, occurs at the output terminal 94. These three pulsesare displayed on the third horizontal line on the cathode ray tube face.

It should be apparent from the foregoing description how, by the use ofthe slightly altered output circuitry, it

is possible to generate signals for representing any character desiredwhen displayed on the face of the cathode ray tube, by cutting out thepattern of the shield 104 in the shape of the character desired to bedisplayed. All that is required for generating signals to representanother character is to merely separate the two printed circuit boards,remove the shield present therebetwee-n, and insert the new shieldhaving the new pattern in its place. The printed circuit boards may thenbe pressed together by any suitable clamping means. A plurality of thesecharacter signals generators may be employed and selectively connectedby means of any suitable known selecting mechanisms to cathode raydisplay apparatus.

A simple arrangement for such a selective display device is shown inFIGURE 7. A single ring counter 110, driven by a clock pulse source 112,may be employed. The output of the ring counter drives five coincidencegates for each character signal generator employed. Each five gates isdesignated as a gate set. Thus, in FIGURE 7, three gate setsrespectively 120,122 and 124 are shown receiving one output from thering'counter 110 and a second selecting output from a characterselection source 126 Each one of the character signal generators hasitsoutput connected to the cathode ray display apparatus 128. Thesynchronizing signals from the ring counter 110 are also applied to thecathode ray display apparatus 128; The character selection source 126enables one of the sets of gates 120 through 124.v The ring counter 110in response to the clock signals applies its output successive ly toeach one of the five gates in the selected set. The character signalgenerator associated with the selected set will have the circuitry shownin" either FIGURE 3 or FIGURE 5, commencing with the drive amplifiers 64through 72, which receive the outputs of the selected gate set. Theoutput of the delay line of each character. signal generatoris connectedto the cathode ray display apparatus 128. The arrangement shown maybeemployed for generating words, or sentences, orany other display.

There has accordingly been shown and described herein a novel, usefuland simple arrangement for generating signals in a pattern whereby upondisplay by-cathode ray tube apparatus the signals represent a character.

We claim: 1. A character signal generator comprising a plurality oftransformers each of which has a primary winding and .series, means formagnetically shielding the secondary windings of predetermined ones ofsaid transformers from the primary windings of said predetermined onesof said transformers for preventing a voltage from being induced in saidsecondary windings in response totcurrent in'said.

primary winding, means for sequentiallyv applying a current pulse toeach one of the columns of a series connected primary winding, delaymeans to which each one of said rows of series connected secondarywindings are connected for sequentially arranging output f'rom thesecondary windings of transformers which are disposed in a single columnof transformers, and'means for displaying in successive lines aftereachenergization of a different column of series connected primarywindings .the output of said delay means. g Y

2. A character signal generator comprising'a plurality oftransformers,each said transformer having a primary and secondarywinding, said transformers being arranged in columns and rows, meansconnecting all the primary windings of transformers in each column inseries, means connecting all the secondary windings of the transformersin each row in series, means for magnetically shieldingthe secondarywindings of predetermined onesof said transformers from their primarywindings, means for apply- 7 ing a current pulse in sequence to each oneof the columns of series connected primary windings, whereby a voltageis induced in the secondary windings of those'transformapplying currentpulses to said columns of primary windings and to the outputs of saidsecondary windings for displaying a predetermined character asdeterminedfby 3. A character signal generator comprisinga plurality oftransformers arranged in columns and rows, each of said transformershaving a primarywinding and a secondcitingin sequence with ajc'u'rrentpulse each one of said columns of said series connected primarywindings, a delay line having taps spaced therealong, means connectingeach of said rows of series connected secondary windings to a differenttap along said delay line, display means connected to the output of saiddelay line, and means for applying to said display means synchronizingsignals from said means for sequentially exiting said columns of seriesconnected primary windings for displaying the signals received by saiddisplay means from said one end 'of said delay line.

4. 'A character signal generator as recited in claim 3, wherein theprimary windings of said plurality of transformers comprise printedcircuit wiring deposited on a first board, the secondary windings ofsaid plurality of transformers comprise printed circuit wiring depositedupon a second board, said second board being superimposed upon saidfirst board to provide magnetic coupling between the primary andsecondary winding, and said shield means for preventing magneticcoupling between the primary windings and secondary windings ofpredetermined ones of said transformers comprises a magnetic shieldwhich is inserted between said first and second boards.

5. A character signal generator comprising a plurality -of transformersarranged in columns and rows, each of said transformers having a primaryand secondary winding, means connecting in series the primary windingsof each column of transformers, means connecting in series the secondarywindings of each row of transformers, shield means for preventingmagnetic coupling between predetermined ones of said primary andsecondary windings in QCCOIdHllCfliWlih the shape of a predeterminedcharacter desired to be displayed, a counter having each ings of eachrow of transformers to a different one of said delay line tappingpoints, means for energizing said counterto sequentially advance itscount to sequentially excite the series connected primary windings ofeach column of transformers, and means to which said delay line outputis applied for displaying in successive lines after each output of saidcounter the signals received from the series connected secondarywindings, of said rows .of transformers. I a

'6. A character signal generator comprising a plurality of transformersdisposed in rows and columns, each said transformer having a primary'andsecondary winding, means connecting the primary windings of each columnof transformers in series, means connecting the secondary windings ofeach row of transformers in series, shield means for preventing magneticcoupling between predetermined ones of said primary and secondarywinding in accordance with the shape of a predetermined characterdesired to be displayed, a ring counter, means for ad- ;vancing saidring counter through its successive count states, means for connectingeach count state output to the series connected primary windingsrof adifferent column of transformers, an inhibit gate for each row ofsecondary windings of each row of transformers to the the location ofthe ones of said transformers having their. secondary windings shieldedfrom their primary windings."

ary winding, means connecting -in series the primary windings of eachcolumn of transformers, means' conpredeterminedones of said transformersinaccordance.]'

with a character desired to be displayed, means for exor inhibit gatefor that row to inhibit said gate in the presence 1 of an output fromthe secondaryiwinding in the associated row of transformers, means forapplying a pulse signal to every one of said inhibit gates each timesaid counter advances its count state whereby said inhibit gates willprovide output signals when there is no inhibit signal "received fromthe secondary windings in the row of transformers with which itis'associated, means to which the signals from said inhibit gates areapplied for spacing said signals by predetermined amounts, and means fordisplaying in successive lines after eachicountstate output,

the output of said means for spacing signals alongra different line toproduce said predetermined character.

7. In a character display system of the type wherein characters areformed on a display device as a plurality of successive adjacent linesalong each of which are spots displaced from one another, apparatus forproviding signals from which said spots are derived comprising aplurality of transformers having primary windings in the form of printedcircuit conductors on one board and secondary windings in the form ofprinted circuit conductors on a second board, said first and secondboards being superimposed on one another, and a magnetic shieldpositioned between the first and second boards for preventing magneticcoupling between the primary and secondary windings of predeterminedones of said transformers in accordance with the signals desired forforming a predetermined character.

8. In a character display system of the type wherein characters areformed on a display device has a plurality of successive adjacent linesalong each of which are spots displaced from one another, apparatus forproviding signals from which said spots are derived comprising aplurality of transformers disposed in rows and columns, each transformerhaving a primary winding and a secondary winding, the primary windingsof each separate column of transformers being connected in series, thesecondary windings of each separate row of transformers being connectedin series, said separate series connected columns of primary windingscomprising printed circuit conductors on a first substrate, saidseparate rows of series connected secondary windings comprising printedcircuit conductors on a second substrate, said second substarte beingsuperimposed on said first substrate, a magnetic shield inserted betweensaid first and second substrate, said magnetic shield being shaped forpreventing magnetic coupling between predetermined ones of saidtransformer primary and secondary windings in accordance with acharacter desired to be displayed, means for successively applyingcurrent pulses to each separate column of series connected primarywindings, means for spacing the signals induced in said rows of seriesconnected secondary windings in response to the succesive excitation ofsaid columns of primary windings, and means for displaying in successivelines the output of said means for spacing to produce said predeterminedcharacter.

References Cited by the Examiner UNITED STATES PATENTS 2,814,031 11/57Davis 340174 2,856,597 10/58 De Mo tte 3-40-l66 6,012,240 t1-2/6l Klahn340-l66 3,027,548 3/62 Vaughn 340174 3,103,658 9/63 Chiang 340324.1

NEIL C. READ, Primary Examiner.

1. A CHARACTER SIGNAL GENERATOR COMPRISING A PLURALITY OF TRANSFORMERSEACH OF WHICH HAS A PRIMARY WINDING AND A SECONDARY WINDING, SAIDTRANSFORMERS BEING DISPOSED IN AN ARRAY OF COLUMNS AND ROWS, MEANSCONNECTING ALL THE PRIMARY WINDINGS IN EACH SEPARATE COLUMN OFTRANSFORMERS IN SERIES, MEANS CONNECTING ALL THE SECONDARY WINDINGS OFSAID TRANSFORMERS IN EACH SEPARATE ROW INSERIES, MEANS FOR MAGNETICALLYSHIELDING THE SECONDARY WINDINGS OF PREDETERMINED ONES OF SAIDTRANSFORMERS FROM THE PRIMARY WINDINGS OF SAID PREDETERMINED ONES OFSAID TRANSFORMERS FOR PREVEANTING A VOLTAGE FROM BEING INDUCED IN SAIDSECONDARY WINDINGS IN RESPONSE TO CURRENT IN SAID PRIMARY WINDING, MEANSFOR SEQUENTIALLY APPLYING A CUR-